package org.example;


import cn.hutool.core.util.StrUtil;
import com.sun.deploy.util.StringUtils;
import lombok.Cleanup;

import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;

/**
 * @author JNPF开发平台组
 * @version V3.1.0
 * @copyright 引迈信息技术有限公司
 * @date 2021/3/16 10:51
 */
public class Md5Util {
    /**
     * 默认的密码字符串组合，用来将字节转换成 16 进制表示的字符,Apache校验下载的文件的正确性用的就是默认的这个组合
     */
    protected static char[] hexDigits = {'0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'a', 'b', 'c', 'd', 'e', 'f'};
    protected static MessageDigest messagedigest = null;

    static {
        try {
            messagedigest = MessageDigest.getInstance("MD5");
        } catch (NoSuchAlgorithmException e) {
            e.printStackTrace();
        }
    }

    /**
     * 获取文件MD5值
     *
     * @param file
     * @return
     * @throws IOException
     */
    public static String getFileMd5String(File file) throws IOException {
        @Cleanup InputStream fis = new FileInputStream(file);
        byte[] buffer = new byte[1024];
        int numRead = 0;
        while ((numRead = fis.read(buffer)) > 0) {
            messagedigest.update(buffer, 0, numRead);
        }
        fis.close();
        return bufferToHex(messagedigest.digest());
    }

    /**
     * 密码字符串MD5加密 32位小写
     *
     * @param str
     * @return
     */
    public static String getStringMd5(String str) {
        //MessageDigest是线程不安全的，新建实例保证不出错
        MessageDigest messagedigest;
        try {
            messagedigest = MessageDigest.getInstance("MD5");
        } catch (NoSuchAlgorithmException e) {
            throw new RuntimeException(e);
        }
        if (StrUtil.isEmpty(str)) {
            return "";
        }
        byte[] buffer = str.getBytes();
        messagedigest.update(buffer);
        return bufferToHex(messagedigest.digest());
    }

    public static String bufferToHex(byte[] bytes) {
        return bufferToHex(bytes, 0, bytes.length);
    }

    private static String bufferToHex(byte[] bytes, int m, int n) {
        StringBuffer stringbuffer = new StringBuffer(2 * n);
        int k = m + n;
        for (int l = m; l < k; l++) {
            appendHexPair(bytes[l], stringbuffer);
        }
        return stringbuffer.toString();
    }

    private static void appendHexPair(byte bt, StringBuffer stringbuffer) {
        char c0 = hexDigits[(bt & 0xf0) >> 4];
        char c1 = hexDigits[bt & 0xf];
        stringbuffer.append(c0);
        stringbuffer.append(c1);
    }

    private static final String toHex(byte[] hash) {
        if (hash == null) {
            return null;
        }
        StringBuffer buf = new StringBuffer(hash.length * 2);
        int i;

        for (i = 0; i < hash.length; i++) {
            if ((hash[i] & 0xff) < 0x10) {
                buf.append("0");
            }
            buf.append(Long.toString(hash[i] & 0xff, 16));
        }
        return buf.toString();
    }

    public static String hash(String s) {
        try {
            return new String(toHex(getStringMd5(s).getBytes("UTF-8")).getBytes("UTF-8"), "UTF-8");
        } catch (Exception e) {
            return s;
        }
    }

    public static void main(String[] args) {
        // 生成 secret key
        String secretkey = RandomUtil.uuId();
        String password = "123456";
        // 对密码第一次md5加密
        String pwd=  Md5Util.getStringMd5(password);
        // 对第一次加密的结果和密钥进行md5加密
        String pwdFinal = Md5Util.getStringMd5(pwd.toLowerCase() + secretkey.toLowerCase());

        System.out.println("Secretkey is " + secretkey + ", Password is " + pwdFinal);
    }
}
